1. Field of the Invention
The present invention relates to a floating type head slider on which a magnetic head for reading and recording information such as data and a program from/on a magnetic disk is mounted and a magnetic disk unit provided with the head slider.
2. Description of Related Art
For example, in a computer system, a hard disk is used for a magnetic disk unit. A magnetic film is formed on both surfaces of a magnetic disk built in the hard disk, data and the like are recorded in a track on the magnetic film, and data and the like recorded in a track on the magnetic film are read by a magnetic head mounted on a head slider floating over the surface of the magnetic disk.
As a mechanical part for driving a floating type head slider on which a magnetic head is mounted and a driving part for driving a magnetic disk are beforehand built in a housing, data and the like can be recorded in relatively high density and high-speed access to recorded data and the like is enabled.
FIG. 16 is a perspective drawing showing a constitutional example of a hard disk which is an example of a conventional type magnetic disk unit.
In the hard disk 1, a spindle motor 9 is arranged on the reverse side of the flat part of a housing 2 formed of an aluminum alloy and the like and a magnetic disk 3 rotated at fixed angular velocity by the spindle motor 9 is provided.
Further, an arm 4 is attached around a vertical shaft 4a to the housing 2 so that the arm can be swung. A voice coil 5 is attached to one end of the arm 4, one end of a suspension 8 is attached to the other end of the arm 4 and further, a head slider 6 is attached to the other end of the suspension 8. Magnets 7a and 7b are attached on the housing 2 so that the voice coil 5 is held between the magnets. A voice coil motor 7 is formed by the voice coil 5 and the magnets 7a and 7b.
In such constitution, when current is supplied to the voice coil 5 from an external device, the arm 4 is turned around the vertical shaft 4a according to force generated by the magnetic field of the magnets 7a and 7b and current which flows in the voice coil 5. Hereby, the head slider 6 attached to the other end of the suspension 8 extended from the arm 4 is swung in the substantially radial direction of the magnetic disk 3 as shown by an arrow X.
In the head slider 6, rails 6a and 6b which function as air bearing surfaces are formed on both sides in a direction in which the head slider is swung over the magnetic disk 3 under the head slider (hereinafter called a cross direction) as shown in FIG. 17. A magnetic head 10 is mounted at the rear end of one rail 6a.
Hereby, when the head slider 6 approaches the surface of the rotated magnetic disk 3, it receives floating force generated by air flow among the rails 6a and 6b and the surface of the magnetic disk 3 generated as the magnetic disk 3 is rotated. The head slider 6 seeks over the magnetic disk 3, being run with the head slider floating by a minute interval (floated quantity) from the surface of the magnetic disk 3 by the above floating force and the head slider 10 mounted on the head slider 6 reads or records data and the like from/in a predetermined track and the like of the magnetic disk 3 without coming in contact with the magnetic disk. The above floated quantity is generally approximately 0.1 .mu.m.
Generally, to enhance the electromagnetic transductional characteristic of a magnetic head, it is effective to reduce magnetic spacing between the head slider and a magnetic disk. For one of methods of reducing the above magnetic spacing in the above hard disk 1, there is a method of reducing the floated quantity of the head slider 6. However, when the floated quantity of the head slider 6 is reduced, a hazard such as the head slider 6 may be crushed when shock is applied to the hard disk 1 is increased and the above method is a negative factor in view of the reliability of the hard disk 1.
Therefore, the floated quantity of the head slider 6 is set to a value in which the electromagnetic transductional characteristic of the head slider 10 and the reliability of the hard disk 1 are balanced. That is, the minimum clearance between the head slider 10 and the magnetic disk 3 is required to be always kept fixed. For that, it is desirable that the floated quantity of at least the rail 6a on the side on which the head slider 10 is mounted of the two rails 6a and 6b of the head slider 6 is lower than that of the rail 6b on the side on which the head slider 10 is not mounted.
It is because conversely, if the floated quantity of the rail 6b on the side on which the head slider 10 is not mounted is lower than that of the rail 6a on the side on which the head slider 10 is mounted, the floated quantity of the rail 6b on the side on which the head slider 10 is not mounted is required to be set to the above balanced value, and therefore, as the floated quantity of the rail 6a on the side on which the head slider 10 is mounted is higher than the above balanced value, magnetic spacing between the head slider 10 and the magnetic disk 3 is wasted by the difference.
As described above, to set the floated quantity of the rail 6a on the side on which the head slider 10 is mounted so that it is lower than the floated quantity of the rail 6b on the side on which the head slider 10 is not mounted, heretofore, the head slider 6 is bonded to the suspension 8 with the center line of the suspension 8 and the center line of the head slider 6 dislocated by predetermined distance as shown in FIG. 18 so that a larger spring load is applied to the rail 6a on the side on which the head slider 10 is mounted.
As described above, as the conventional type head slider 6 is required to be bonded with the center line and the center line of the suspension 8 displaced by predetermined distance, there is a problem that a precise positioning jig is required. As the upper head and the lower head are different in the direction of displacement, there is also a problem that positioning jigs dedicated to each are required.